Milk frother appliance

ABSTRACT

An appliance that is dockable onto a drinks preparation machine, for preparing frothed milk and, for this purpose, includes at least one connection for steam produced by the drinks preparation machine, as well as an interface for electrical current delivered from the drinks preparation machine. The appliance also includes a milk frothing unit with a gear pump. The gear pump at an inlet side is connected to a milk feed conduit and to an air feed. A mixing nozzle is provided on a path of milk delivered by the gear pump, to which mixing nozzle this milk, the steam as well as the air can be fed.

BACKGROUND OF THE INVENTION Field of the Invention

The invention generally relates to the field of appliances for preparing drinks and, more particularly, to an appliance for producing milk froth and milk drinks, the appliance being able to be docked onto a drinks preparation machine, as well as to a drinks preparation system with such an appliance.

Description of Related Art

Milk frother appliances as integrated modules of coffee machines or as separate appliances that are dockable onto coffee machines are known. EP 2 047 779 discloses a coffee machine with a dockable milk module, wherein hot steam from the coffee machine is used to froth milk, which is sucked out of a vessel of the milk module in accordance with the Venturi principle.

The solution that is based on the Venturi principle, as that one described above, is only capable of preparing hot milk froth. However, the preparation of cold milk froth is often also desirable. EP 2 326 224, for example, shows a milk frother that includes a gear pump as a central froth-producing element. At the inlet side of the gear pump, this sucks air and milk that is simultaneously frothed when being delivered by the gears and at the outlet side is dispensed as frothed milk. Optionally, steam can be additionally fed in the gear pump, so that the dispensed frothed milk is warm.

SUMMARY OF THE INVENTION

It is an object of the present invention, to provide an appliance for producing milk froth, which overcomes disadvantages of the state of the art and which permits the production of milk froth for a multitude of possible cases of use.

An appliance according to the invention, for preparing frothed milk, is dockable onto a drinks preparation machine and for this purpose includes at least one connection for steam produced by the drinks preparation machine, as well as an interface for electrical current which is provided by the drinks preparation machine. The appliance further includes a gear pump. The gear pump at an inlet side is connected to a milk feed conduit and to an air feed. A mixing nozzle, to which this milk, the steam as well as air can be fed, is moreover present on a path of this milk delivered by the gear pump.

The group with the gear pump, the associated air feed as well as the conduits, which are necessary of the transport of liquid to and away from the gear pump, but without the mixing nozzle is termed as “milk frothing unit” in this text. In embodiments, the milk frothing unit can be configured such that an operating parameter is adjustable in a manner depending on a reading and/or operator input. What is meant by “adjusting” here is exerting an influence upon the at least one operating parameter of the milk frothing unit, which influences how this acts during an active milk frothing operation. The adjustability therefore is different to a mere “on/off”, as is known from the state of the art. The adjustability in particular is effected in a manner such that a parameter, which is specified by the user and/or specified by a control, has an influence on the characteristics and/or quantity of the produced milk froth. In particular, an adjustable operating parameter can be a speed of the gear pump or the fed air quantity (which can be regulated for example by a valve unit with an adjustable valve opening).

The mixing nozzle in particular can be designed such that inflowing steam—which gets from the steam connection into the mixing nozzle—achieves a suction effect in the manner known per se. The sucking of air and the intermixing with milk fed to the mixing nozzle can be effected by way of this suction effect, by which means frothed milk can be produced, wherein this milk is warm on account of the heat released by the steam, wherein this heat predominantly, but not exclusively, is released to the milk as condensation heat. This suction effect can be based on Bernoulli's law (wherein the mixing nozzle can then be designed for example as a Venturi nozzle) and/or on impulse transmission, as is known per se in combination with so-called jet pumps.

In embodiments, the feed of air into the mixing nozzle can have a common inlet with the feed of air to the inlet of the gear pump and be effected, for example, in a manner coming from the milk frothing unit as well as, as the case may be, likewise can be regulated by way of a suitable regulating means, which are described in more detail hereinafter.

The feed of air into the mixing nozzle can alternatively also have a separate inlet and be formed, for example, by way of a valve, which leads outwards into the surroundings and which, given a feed of steam, automatically opens on account of a vacuum in the mixing nozzle, which is produced by way of this. In particular, such a valve can be designed as a duckbill valve.

The mixing nozzle can be configured such that a suction effect of the described type also exists for the milk flowing into the nozzle. The latter however is not necessary on account of the possibility of delivering the milk by the gear pump. In contrast, the milk can also go into the mixing nozzle at a location, at which essentially no vacuum exists.

The air feed at the inlet side of the gear pump can be designed such that it can be switched on and off. A switching-off of the air feed in particular makes sense if warm milk froth is to be produced in any case, and the gear pump is only used for delivering (transporting) the milk.

The mixing nozzle can be arranged, for example, directly above the milk froth outlet.

The appliance for preparing frothed milk (milk frother appliance) can prepare cold as well as warm frothed milk.

Milk—in particular from a milk vessel belonging to the milk frother appliance—is sucked by way of the gear pump, and air is also simultaneously sucked through the air feed, for the preparation of cold frothed milk. Frothed milk thus arises at the outlet side of the gear pump. A throttle can yet be present at the outlet side of the gear pump, and such a throttle can be formed by way of a narrowing of the channel for the frothed milk.

The frothed milk can be dispensed via a milk froth outlet. The mixing nozzle can be located on the path from the gear pump to the milk froth outlet, wherein no steam is led into this nozzle and therefore also no air is sucked into it, if cold, frothed milk is to be prepared. The mixing nozzle in this case only serves for the passage of the frothed milk.

It is also possible to keep the conduits for cold milk froth coming from the pump and for warm milk froth created in the mixing nozzle, separate from one another up to the outlet, i.e. the cold milk froth is then not led through the mixing nozzle. The milk froth outlet can then include openings for the cold and the warm milk froth that are separate from one another, for example ones which are concentric to one another. Completely separate milk froth outlets, which are significantly spatially separated from one another and are for the cold and the warm milk froth, are also conceivable.

Milk can likewise be sucked and delivered via the gear pump, for preparing warm frothed milk. Apart from the milk, steam from the drinks preparation machine is also fed to the mixing nozzle. This produces the suction effect, which has been described above. Warm, frothed milk arises due to the mixing of cold milk, steam and air in the mixing nozzle.

The feed of air to the gear pump—inasmuch as this possibility is envisaged—can optionally be switched off given the preparation of warm frothed milk. Inasmuch as this is not envisaged or not desired, the milk is pre-frothed whilst still in the cold condition, inasmuch as the mixing nozzle is located after the gear pump, as is preferred.

The feed of air to the mixing nozzle can also be optionally designed in a closable manner, and then the preparation of non-frothed, warm milk is also possible. The user can then also use the gear pump, in order to merely deliver the cold milk.

In embodiments, the milk frothing unit includes a housing. This housing forms a gear pump chamber under certain circumstances together with a cover (which here is counted as belonging to the housing) and/or with other elements. This chamber is delimited to the bottom by a seal. The seal is designed as a continuous object with at least one valve opening for the sucked milk. A conduit for the milk to be sucked as well as:

-   -   an electric motor of the gear pump which drives the gears via a         shaft projecting through the plane of the seal;     -   a valve unit for the feed of air;     -   a conduit for the feed of air;     -   an air feed conduit leading to the gear pump; and/or     -   a transition into a docking element, wherein this docking         element serves for docking onto the drinks preparation machine         and includes the connection for the steam as well as the         interface, is located beneath the seal and fastened on the         housing or is formed by this housing.

These elements can be present beneath the seal, in each case alone or in an arbitrary combination.

A duckbill valve or duckbill valves can be formed by the seal itself, for the transit of milk from the lower side to the upper side, as well as, as the case may be, for the transit of air from the lower side to the upper side, as well as, as the case may be, for the transit of cleaning water or cleaning steam, which can be fed by a separate conduit, into the liquid conduit.

In a very simple manner, this design permits a sealing between on the one hand the (upper-side) region, in which frothing takes place, and on the other hand the region of the feeds and of the electrically operated parts. Important advantages concerning the cleaning also result due to the simple construction with a single seal.

Additionally to the mentioned connection for the steam, the milk frothing appliance can include a further connection for water that is hot, for example, and/or for steam, which is/are delivered by the drinks preparation machine, the water or the steam being able to be used for through-rinsing and for cleaning. A conduit from this connection for the cleaning water or for the cleaning steam can be present and this, for example, runs out into the milk frothing unit, and as the case may be serves for through-rinsing and, under certain circumstances also for sterilising the gear pump including the feed conduits and outgoing conduits. A valve, for example a duckbill valve, can be present between this conduit and the inlet side of the gear pump, and this valve automatically closes when a lower pressure is present in the region in front of the gear pump, than in the conduit, which as a rule will be the case during operation of the gear pump without feeding cleaning water or cleaning steam.

In embodiments, the drinks preparation machine can also include an air discharge location, through which air can be discharged from the machine's internal, in particular electronically controlled valve unit, to the milk frothing appliance, for example to its gear pump as the case may be, in a regulated manner. In such embodiments, the milk frother appliance can additionally include an air connection for the air that comes from the drinks preparation machine and is delivered to the milk frothing unit.

As already mentioned, the milk frothing unit can include a container for receiving milk. In embodiments, the container and the milk frothing unit with regard to their geometry are matched to one another such that the milk frothing unit can be placed onto the container and closes this off. A lid can optionally be present, and this fits onto the milk frothing unit placed on the container as well as directly onto the container, which is very practical if the container is not empty after use and is to be kept in the fridge.

The invention also relates to a drinks preparation system with an appliance of the described type and additionally with a drinks preparation machine. The drinks preparation machine—for example a coffee machine—for example includes a water container, a water pump and a water heater. A brewing chamber for preparing the hot drink from heated water by way of extraction from an extraction material is also present. The drinks preparation machine can also include an electronics unit which includes the previously discussed activation and, as the case may be, a regulation of the valve unit or—if this unit is part of the milk frother appliance—is communicatingly connected to it. Inputs of the user are preferably effected at an input location of this electronics unit, and a recognition of a coffee capsule with the extraction material is likewise effected by this electronics unit as the case may be. The control of the flow of steam is also effected by this electronics unit.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiment examples of the invention are hereinafter described by way of figures. The same or analogous elements are indicated in the figures by the same reference numerals. There are shown in:

FIG. 1 is a view of the appliance for preparing frothed milk (milk frother appliance);

FIG. 2 is an exploded representation of the milk frother appliance;

FIG. 3 is an exploded representation of the milk frothing unit of the milk frother appliance;

FIG. 4 is a view of the milk frothing unit sectioned along a horizontal plane;

FIG. 5 is a partial view of the seal of the milk frothing unit with elements of the gear pump;

FIG. 6 is a view of the upper main housing part of the milk frothing unit, which is sectioned along a horizontal plane;

FIG. 7 is a view of the upper main housing part from below;

FIG. 8 is a view of the upper main housing part, which is sectioned along a vertical plane;

FIG. 9 is a view of the valve unit of the milk frothing unit;

FIG. 10 is an exploded representation of the valve unit;

FIGS. 11a-11c show the valve unit in a plan view, side elevation and front elevation, respectively;

FIG. 12 is a view of the milk frothing unit with a valve unit, from above;

FIG. 13 is a representation of the milk frothing unit, sectioned along a plane through the valve unit;

FIGS. 14a-14b are views of the docking element, obliquely from above and below, respectively;

FIGS. 15a-15d are views of the supplementary part;

FIGS. 16a-16b are views of the main body;

FIGS. 17a-17d are representations of the docking element without an external housing;

FIGS. 18a-18c are representations of parts of the appliance, from which the function of the docking element is evident;

FIG. 19 is a view of the drinks preparation system with the milk frothing appliance;

FIG. 20 is a detail of the drinks preparation system, represented sectioned along a vertical plane;

FIG. 21 is a detail concerning the docking of milk frothing appliance onto the drinks preparation machine;

FIG. 22 is a view of a detail of the milk frother appliance;

FIG. 23 is a schematic diagram of the drinks preparation system;

FIG. 24 is a sectioned representation of the milk frother appliance, which is drawn only partly, with the docking element, in an alternative embodiment; and

FIG. 25 is a view of this milk frother appliance in the alternative embodiment.

DETAILED DESCRIPTION OF THE INVENTION

The appliance 1 for preparing frothed milk (milk frother appliance) is represented as a whole in FIG. 1. FIG. 2 shows an exploded representation of its parts.

The appliance 1 includes a milk container 3, a milk frothing unit 5 and a lid 6.

The milk container 3 is designed in a doubled walled manner in the represented embodiment, for thermal insulation purposes, but single-walled designs are also possible. It can be transparent or include a viewing window for checking the level of the milk.

The milk container 3 and lid 6 can be matched to one another such that the lid 6 can also be placed directly onto the milk container 3, without the milk frothing unit 5 being arranged therebetween, by which means the filled milk container with the lid can be placed into the fridge, for example. The milk container and the lid can also be cleaned in a simple manner, and be designed, for example, in a dishwasher-safe manner.

The elements of the milk frothing unit 5 are represented in an exploded representation in FIG. 3. A lower main housing part 11 carries an electric motor 13 belonging to the gear pump, as well as an upper main housing part 14. A lateral window 12 is formed in the upper main housing part.

The upper main housing part 14 forms a roughly circularly cylindrical trough, in which gears 17 of a gear pump are arranged. The gears 17 of the gear pump are driven via a shaft 19, which is connected to the electric motor 13. A seal 21 seals the trough to the bottom.

In addition to the gears, the shaft and the electric motor, the gear pump can also have its own housing, or such can be integrated into the main housing or other parts, for example into a milk frothing unit cover 16. In the represented embodiment example, the milk frothing unit cover 16 is shaped out such that a pump chamber encompassing the gears 17 is formed between the seal 21 and the milk frothing unit cover 16, on account of an arching 15 (also clearly visible in FIG. 12).

A valve unit 20 is also fastened on the main housing 11, 14.

A milk suction tube 18 (not represented in FIG. 3) extends downwards from the plane of the gear pump and projects into the milk container 3 and almost up to the base of this, in the assembled condition of the appliance 1.

A connection shaped part 22 is further present beneath the gear pump. This part seals the window 12 and simultaneously forms a feed-through for connection of conduits of the milk frother, which are described hereinafter and are fastened on the one hand to the main housing, and on the other hand to a docking element.

Likewise visible in FIG. 3 are a spacer 23 and a motor seal element 24.

The docking element includes a docking element body, which is protected by a docking element housing 26. The docking element body is formed by a main body 25 and a supplementary part 27, which is described in yet more detail hereinafter. It can already be seen in FIG. 3 that the supplementary part 27 includes a downwardly projecting milk froth outlet 28.

FIG. 4 shows a view from above, of the milk frothing unit 5, which is sectioned along a plane lying above the sealing plane defined by the seal 21. The lighter lines in the plan view represent elements running further below, which per se are not visible.

The gear pump is attached above the sealing plane. An upper-side liquid conduit 31 leads to the gear pump. This is connected on the one hand to the milk suction tube 18 and on the other hand to a hot water conduit and/or steam feed conduit 32, via duckbill valves 42, 41 that are formed by the seal 21 and are also clearly visible in FIG. 5. An air feed conduit 34 is connected to the upper-side liquid conduit, which is to say to the gear pump at the inlet side, likewise via a duckbill valve 43, which is formed by the seal.

Arranged behind the gear pump is a feed-through 36 for the delivered milk, which is already frothed, depending on the selected operating condition, through which feed-through this milk again goes downwards through the sealing plane, where it gets through an outgoing conduit 35 into the docking element.

FIGS. 6 to 8 show further views of the upper main housing part 14, which in represented sectioned along a horizontal plane in FIG. 6 and along a vertical plane in FIG. 8 and in a view from below in FIG. 7.

The lower-side conduits are formed by tubes of the connection shaped part 22, which are laid into corresponding channels of the upper main housing part 14. These channels, i.e. the channel 51 for the hot water and/or steam feed conduit 32, the channel 52 for the air feed conduit 34 and the channel 53 for the outgoing conduit 35 are particularly clearly visible in the view from below according to FIG. 7.

The seal 21 (FIG. 8) is clamped between the upper main housing part 14 and the milk frothing unit cover (not shown in FIG. 8). The pump chamber of the gear pump including the gears 17 is formed between the milk frothing unit cover and the upper main housing part, due to the arching 15 in the milk frothing unit cover (FIG. 3; FIG. 12).

A further optional feature can be seen in FIG. 8. The feed-through 36 for the delivered milk that is already frothed depending on the selected operating condition is narrowed in the manner of a throttle. A certain backpressure is produced in the gear pump by way of this, on account of which pressure the flow quantity regulates itself. This backpressure contributes to an efficient frothing of the cold milk.

FIG. 9 shows a view of the valve element 20, FIG. 10 shows an exploded representation of the valve unit and FIGS. 11a-11c show the valve unit in a view from above, sectioned along the line E-E in FIG. 11a and along the line D-D in FIG. 11 a.

FIG. 12 shows a view of the milk frothing unit with a valve unit 20, without the docking element and milk suction tube, from above, and FIG. 13 shows this sectioned along a vertical plane going through the line 213 in FIG. 12.

The valve unit 20 includes two valve elements in a common valve housing 61. Each valve element includes a closure element 62, which carries a sealing element 63 and is movable along an axis, in the selected installation situation along the vertical axis. The upward movement is effected by way of an electromagnet 64 and against the force of a spring 65 stressed between the electromagnet (or the valve housing) and a securing ring 66. The heads of the valve elements, which are formed at the upper side by the closure elements and seal elements, project through openings in the upper main housing part 14 (see FIGS. 12 and 13). In the closed condition, a seal portion 67 of the respective seal element 63 is pressed by the force of the spring against a surface of the upper main housing part 14, along the periphery of the respective opening.

With both valves, a valve chamber 71 forms in each case between the respective wall of the upper main housing part 14 and a seal 68. An inflow opening forms when the closure element with the sealing element 63 is lifted by the electromagnet, through which inflow opening air can flow from the outside into the respective valve chamber 71 and from this can get into a (common) air feed conduit through an air connection stub or branch 73.

The two valve elements can be actuated independently of one another and can be opened in each case individually or together. Different valve opening conditions can be created by way of this. As a whole, four valve opening conditions result by way of either only one of the valve elements being open and the other closed, both being open or both being closed.

In embodiments, it can also be meaningful for the valve elements and/or the size of the respectively formed inflow opening to be selected to a differently large extent and/or for the air, which is admitted by one of the valve elements, to be subjected to a significantly greater flow resistance than the air admitted by the other valve element. The four different defined opening conditions are then quantitatively different. For example, the inflow opening of one of the valve elements can be double the size of the inflow opening of the other valve element, so that the conditions “0” (air valve completely closed), “⅓” (the smaller valve element open), “⅔” (the larger valve element open) and “1” (both valve elements open) can be selected.

An airflow regulating element such a 3/2-way valve for example (not drawn) and by way of which the path between the valve chambers 71 and the mixing nozzle or the path between the valve chambers and the entry of the gear pump can be opened and the respective other path can be closed, can be arranged in a manner connected downstream of the valve unit in the airflow direction, in order to regulate whether the mixing nozzle or the gear pump is to be fed with air. Such an airflow regulating element, however, can also be done away with, wherein the regulation is then effected automatically by the respective valve elements, by way of these only opening due to a vacuum at the outlet side, and in this manner preventing a backflow of frothed milk into the respective path, which is not required.

The construction and manner of action of the docking element are described hereinafter by way of FIGS. 14a-14c . FIGS. 14a and 14b show views of the docking element obliquely from above and obliquely from below respectively. FIGS. 15a and 15b show the supplementary part 27 in an unfolded condition and FIGS. 15c and 15d in a folded condition. FIGS. 16a and 16b show the main body 25. FIGS. 17a, 17b and 17c show the docking element sectioned along the planes A-A, B-B and C-C in FIG. 17d . FIG. 18a shows a view of the appliance from above, and FIGS. 18b and 18c show sections of sectioned representations of the appliance sectioned along the planes A-A and B-B in FIG. 18a respectively.

The face-side end, which, for example, lies at the front in FIGS. 14a and 15c , is coupled onto the coffee machined on operation, whereas the opposite end can be coupled onto the milk frothing unit 5.

The main body 25 as a whole can be designed as a shaped body of a suitable, heat-resistant plastic and be manufactured, for example, as an injection moulded part. The supplementary part 27 is manufactured from silicone for example. It is of one piece and as a whole is designed in an extensive (sheet-like) manner with functional elements, which are integrally formed thereon. The entirety of the extensive sections is here indicated as a “base”. Joints 81, which are formed by continuous openings as well as groove-like recesses and which permit an unconstrained folding around the main body 25, are formed between the extensive sections 80. The dimensions of the extensive sections 80 between the grooves are matched to the dimensions of the main body.

Apart from the milk froth outlet 28, the functional elements of the supplementary part 27 are formed by feed-throughs 82-86, and a mixing nozzle element 89.

The main body 25 forms a feed-through conduit 96, which passes from the end at the coffee machine side to the opposite end and which is for cleaning water (cold or heated by the coffee machine) or cleaning steam, the water or steam when required going from the feed-through conduit 96 into the hot water and/or steam feed conduit 32 and from this into the elements to be cleaned, in particular the gear pump. A feed-through 86, 84 of the supplementary part is assigned to the feed-through conduit 96 in each case at the coffee machine side and the milk frother side.

A steam connection, through which steam gets from the coffee machine into the mixing nozzle, is also formed. The steam connection is formed by a feed-through 85 with an assigned valve 87 of the supplementary part 27, the feed-through projecting into a steam connection opening 95 of the main body 25.

On the milk frother side, an opening 92, 93 for the supply of air and milk and into which corresponding feed-throughs 82, 83 of the supplementary part project are formed in the main body in each case. The air feed-through 82 is provided with an assigned valve 88, and this is designed as a duckbill valve just as the steam valve 87 and is of one piece with the remainder of the supplementary part 27.

For the mixing nozzle, the main body 25 includes a mixing nozzle opening 99, into which the mixing nozzle element 89 projects. A milk froth outlet continuation 91 and a positioning ring 94 surrounding this are moreover formed on the underside and cooperate with a corresponding structure 90 of the supplementary part.

The mixing nozzle is formed between the mixing nozzle element and correspondingly shaped chambers of the main body 25.

Steam that is fed in via the steam connection, via the valve 87 gets into a mixing nozzle chamber 97, which one can see particularly well in FIG. 17c , for example. A vacuum is produced in the mixing nozzle chamber 97 by way of the flow of steam, by way of which vacuum air and milk is sucked via the respective feed-throughs 82, 83 (FIG. 17b , FIG. 18b ). Milk froth arises in the mixing nozzle chamber, and goes downwards through the milk froth outlet 28 and into a ready-and-waiting drinks vessel. The frothed milk is warm due to the condensation heat released by the steam.

On account of the small nozzle opening, through which the steam exits at a high speed, the mixing nozzle is thus designed such that a vacuum is produced due to the nozzle effect. This also assists the transport of milk out of the milk conduit, even if the milk is actively delivered due to the gear pump.

The duckbill valves 87, 88 are closed if normal pressure or a slight overpressure prevails in the inside of the mixing nozzle chamber 97. However, they both automatically open if in contrast—as soon as steam flows in—a vacuum prevails on account of the Bernoulli effect and/or on account of impulse transmission.

The feed of air into the mixing nozzle chamber can also be effected directly from the outside, for example via a duckbill valve, instead of through the valve unit, wherein two air paths that are independent of one another then result, on the one hand for the mixing nozzle chamber and on the other hand for the gear pump.

Such a design with the feed of air directly into the mixing nozzle chamber can also be selected for embodiments for example, with which, differing from the example described here, no electrically operated drive means (no electrically operated pump) is present and with which one froths merely in a steam-assisted manner, whilst utilising the suction effect of the mixing nozzle.

The docking element is designed such that the milk froth outlet 28 can lie closely to the outlet for the hot drink. For this purpose, it is arranged in the direct proximity of the end surface 29 coupled to a corresponding surface of the drinks preparation machine. As discussed previously, the distance is not more than 2.5 cm and is preferably even less. The distance as usual is measured as the distance that is measured perpendicularly to the (vertical) plane defined by the end surface, between this plane and the centre point of the exit opening out of the milk froth outlet.

A further optional feature is particularly clearly evident in FIG. 17c . The outlet chamber 86, through which the—generally frothed—milk runs downwards, tapers in the milk froth outlet 28. This, on the one hand, has an additional froth-forming and froth-homogenising effect and, on the other hand, channelises the flow of milk or milk froth.

FIG. 19 shows a view of the complete drinks preparation system 100 with the milk frothing appliance 1 and a coffee machine 101, onto which the milk frothing appliance 1 is coupled. FIG. 20 shows a detail concerning this appliance, with the outlet hood represented in a sectioned manner.

The coffee machine, as is known per se for coffee machines, includes a water container, a water pump and a water heater. A brewing chamber for preparing coffee from heated water by way of extraction from coffee power is moreover present, the coffee powder being provided, for example, in portion capsules that were previously inserted into the coffee machine before the preparation. As an alternative to a portion capsule system, the coffee machine can also be designed as a so called bean-to-cup coffee machine, which also includes a coffee mill and grinds the coffer powder in a portioned manner and feeds it to the brewing chamber. As yet a further alternative, particularly if the coffee machine is designed as a piston machine, i.e. the brewing chamber is formed between a fixed part and a removable piston, one can yet also envisage the coffee power being brought into the brewing chamber by the user in a manner in which it is already in the ground, but loose (non-compacted) condition.

The coffee machine can further include a capture container for spent coffee powder portions (in capsules or in a loose manner, depending on the design of the coffee machine).

A placement platform 103 for placing a drinks vessel or cup is formed on the coffee machine. This can be formed for example by way of a grating, below which a capture dish is located. In embodiments, the placement platform can be height-adjustable in a suitable manner.

A coffee outlet 105, through which brewed coffee runs out and gets into the cup or vessel lying therebelow, is located above the placement platform 103. This outlet is located below an outlet hood 108 that forms part of the coffee machine housing and at least partly covers the outlet to the front and to the sides.

The coffee machine 101 forms a front 106, from which, as is known per se from other coffee machines, on the one hand the placement platform 103 projects and on the other hand, above this, the outlet hood 108 projects.

Here, a milk frother platform 107, onto which the docked milk frothing appliance 1 is placed, likewise projects from the front.

A connection location 110 for the connection of the docking element onto the coffee machine is located in the proximity of the coffee outlet 105 and here, below the outlet hood. This connection location includes a steam delivery location 111 for coupling onto the steam connection of the docking element, and a hot water and/or steam delivery location 112 for coupling onto the feed-through conduit 83. The steam delivery location 111 and the hot water and/or steam delivery location 112 when required are respectively supplied with steam and hot water from the water heater, wherein a multi-way valve in the inside of the coffee machine can selectively feed heated liquid or steam to the brewing module, the steam delivery location or the hot water and/or steam delivery location 112.

The connection location further preferably includes electrical contacts 113, which are represented schematically in FIG. 21. These electrical contacts 113 form an interface on the drinks preparation machine side, and, given a coupled-on docking element, create an electrical connection to corresponding electrical connection element contacts, which are connected to electrical leads leading through the docking element or are formed by these. These electrical leads supply the electrically driven elements of the milk frother appliance, specifically the gear pump, with electricity and control signals as the case may be.

Thereby, it is possible to provide a control of these electrically driven elements in the milk frother appliance (this appliance is then provided with the necessary electronic units and receives control signals from the coffee machine or from an input unit of the milk frother appliance) as well as to accommodate a control of these elements in the coffee machine itself. In the latter case, it is essentially only currents driving the electrically driven elements in accordance with the settings of the control which are led through the electrical leads.

The docking of the milk frother appliance 1 is effected from the side onto the outlet hood 108, and specifically such that the milk frother appliance as a whole is arranged in front of the coffee machine and laterally of the outlet hood 108. The docking is effected, for example, by way of a simple, linear, lateral movement of the assembled milk frother appliance along the front 106.

As one can see in FIG. 21 (showing the milk frother appliance 1 in a decoupled condition) and in particular in FIG. 22 (milk frother appliance without a coffee machine), the electrical leads and the corresponding contacts 98 on the docking element side are formed on the docking element housing 26. The leads can be formed by way of insulated wires or strand conductors or by way of strip conductors of printed circuit (circuit board or flexprint) or the like.

The control of the gear pump in particular is configured such that the speed of the gears 17 can be adjusted, i.e. is selectable. By way of this, the user can control the delivery speed and—according the procedure, which is described in more detail hereafter—as the case may be the preparation of cold frothed milk.

FIG. 23 shows an overview diagram of the milk frother appliance and its coupling onto the drinks preparation machine (coffee machine 101). Air feeds are indicated as “L” in the figure. The letter D indicates a conduit for steam, K a conduit for the hot drink, R a conduit for cleaning water or steam (optional) and S indicates the electricity supply.

The activation 195 here is represented as part of an electronics unit 121 of the coffee machine 101. The electronics unit 121 is configured, for example, to recognise a capsule by way of a measurement and/or to accept a user input, for example via a suitable operating element with a corresponding button, with a touchscreen and/or the like.

Here, the activation 195 is designed such that it can activate the gear pump 7 as well as the valve unit 20, wherein an operating parameter of the gear and/or of the valve unit can be regulated (closed-loop controlled). Activation signals for the valve unit 20 and/or for the gear pump 7 run directly via the connection location 110.

An activation 195′ can also be present completely or partly as part of the milk frother appliance, alternatively to incorporating the activation completely or partly in the coffee machine. This alternative is represented in FIG. 20 in a dashed manner. The electrical energy and, as the case may be, data signals can then be transmitted from the electronics unit to the activation 195′ via the alternative interface 110′.

The mixing nozzle is indicated as a whole by the reference numeral 79.

The milk frother appliance can be operated in the manner described hereinafter.

The gear pump is set in motion whilst at least one of the valve elements of the valve unit 20 is open, for the preparation of cold frothed milk. A vacuum is produced at the inlet side of the gear pump due to the effect of this pump, and this vacuum sucks or draws milk through the milk suction tube 18 and the corresponding duckbill valve 42, as well as air through the valve unit 20 and the corresponding duckbill valve 43. Milk froth therefore arises in the gear pump and gets through the feed-through 36—whose narrowness encourages the formation of fine-pored froth—, the outgoing conduit and the docking element 25, to the milk froth outlet 28 and is dispensed there, wherein generally is drinks vessel 200 is placed upon the platform 103.

The drawing of the generally cold milk out of the milk container 3 via the gear pump is also effected for the preparation of warm frothed milk. This gear pump delivers the milk into the mixing nozzle. Steam from the coffee machine is simultaneously fed to this nozzle via the steam connection. As has already been explained above, the steam produces a vacuum, which, on the one hand, exerts an additional suction upon the milk and assists in the delivery through the gear pump and, on the other hand, sucks or draws air through the likewise at least partly open valve element 20. In the mixing nozzle chamber 97, the milk is mixed with the steam, which heats it up and air is simultaneously intermixed, so that small air bubbles form and milk froth arises. The warm, frothed milk is dispensed through the milk froth outlet.

As mentioned and depending on the situation, a 3/2-way valve or another means can selectively connect the valve element 20 to the gear pump 7 or to the mixing nozzle chamber 97, for the production of cold and warm milk froth respectively. As mentioned, it is also possible for the air feed into the mixing nozzle chamber not to be effected via the valve element 20 but in a direct manner, in which case the supply of air cannot then be regulated by way of a separate means when producing warm milk froth.

One can also envisage the user also only being able to deliver cold milk. In this case, the gear pump is driven, but the valve elements remain closed, and also no steam is fed.

One can also envisage the user being able to prepare warm milk. In this case, the valve element, through which air can get into the mixing chamber, is closed. Should a separate valve for the mixing nozzle chamber be provided (differing from the embodiment represented in the figures), then there is also the possibility of designing the respective valve in a closable manner. A closure of the valve can also be envisaged mechanically by the user by hand, for example. For preparing warm milk, the milk is delivered out of the milk container 3 by way of the gear pump, and steam is simultaneously fed in the mixing nozzle 79, without air also being fed. Warm milk arises due to the mixing of the cold milk with the steam, and this is then dispensed via the milk froth outlet 28.

For on-the-spot cleaning, a vessel is placed below the milk froth outlet 28, and warm water or steam is fed through the feed-through conduit 96 and the hot water and/or steam feed conduit 32. The gear pump is simultaneously set in motion.

The milk frother appliance, however, is also very simple to clean after it has been removed. The milk container 3 and the lid 6 can be designed in a dishwasher-safe manner without any problems. The milk frothing unit 5 can likewise be simple taken apart and cleaned, wherein it is quite useful for the seal 21 to be designed as one piece with the duckbill valves 41, 42, 43 and for it to terminate with the surface of the upper main housing part 14 in a flush manner.

Finally, the docking element is simple to clean due to the fact that the parts which come into contact with milk (main body 25, supplementary part 27) can be simply dismantled, designed in a dishwasher-safe manner and also be simple assembled again in only a single—correct—configuration.

FIGS. 24 and 25 represent an alternative embodiment. This differs from the embodiment, which is described above, in that the supply of air towards the air feed of the gear pump—thus for example to an air feed conduit 34, for example of the described type, or directly to the pump chamber—is not effected by a valve unit belonging to the milk frother appliance, but in a manner coming from the drinks preparation machine. The drinks preparation machine includes, for example, an electronically regulated valve unit for this purpose. This valve unit can be based essentially on the same functioning principle as the valve unit of the milk frother appliance, which is described above. It can alternately have a different functioning principle, for example by way of it only including one valve unit.

For this purpose, the docking element includes an air connection 151 towards the drinks preparation machine. Air gets through an air feed-through 152, which here horizontally passes through the docking element, into the milk frothing unit. In the represented embodiment example, a section of the air feed-through is formed by a tube portion 155 of the docking element housing 26, which however is not a necessity (concerning the air feed-through, a regular cleaning is not a necessity, in contrast to conduits, through which milk flows).

The possibility of the electrical contacts being able to be formed by a contact module 160 is yet indicated in FIG. 25, wherein this module, for example, can include a circuit board or the like and be insertable into a suitable recess in the docking element housing 26

The valve unit arranged in the milk frothing unit is done away with in the embodiment according to FIGS. 24 and 25.

Many further variants are conceivable. Apart from the options which have already been discussed, there is also the possibility of keeping the conduits for cold milk froth (from the pump) and for warm milk froth (created in the mixing nozzle) separate from one another up to the outlet, i.e. the cold milk froth is then not led through the mixing nozzle. The milk froth outlet can then include openings that are separate from one another, for example concentric to one another, for the cold and the warm milk froth. Milk froth outlets for the cold and the warm milk froth and which are completely separate from one another are also conceivable, and the optional conditions for the maximal distance between the milk froth outlet and the hot drinks outlet, which are discussed above, apply in this case, for example for the discharge of the warm milk froth, since it is often this milk froth that is mixed with the hot drink.

LIST OF REFERENCE NUMERALS

-   1 milk frother appliance -   3 milk container -   5 milk frothing unit -   6 lid -   7 gear pump -   11 lower main housing part -   12 window -   13 electric motor -   14 upper main housing part -   15 arching (in the milk frothing unit cover) -   16 milk frothing unit cover -   17 gears -   18 milk suction tube -   19 shaft -   20 valve unit -   21 seal -   22 connection shaped part -   23 spacer -   24 motor seal element -   25 main body (of the docking element) -   26 docking element housing -   27 supplementary part -   28 milk froth outlet -   29 end surface -   31 liquid conduit -   32 hot water and/or steam feed conduit -   34 air feed conduit -   35 outgoing conduit -   36 feed-through -   41 duckbill valve -   42 duckbill valve -   43 duckbill valve -   51 channel for hot water and/or steam feed conduit -   52 channel for air feed conduit -   53 channel for outgoing conduit -   61 valve housing -   62 closure element -   63 seal element -   64 electromagnet -   65 spring -   66 securing ring -   67 sealing portion -   68 seal -   71 valve chamber -   73 air connection stub -   79 mixing nozzle -   80 extensive sections -   81 joint -   82 air feed-through -   83 feed-through (for milk) -   84 feed-through for hot water or steam -   85 feed-through for steam -   86 feed-through for hot water or steam -   87 duckbill valve -   88 duckbill valve -   89 mixing nozzle element -   90 ring (structure) for positioning ring -   91 milk froth outlet continuation -   92 opening for the air feed -   93 opening for the milk feed -   94 positioning ring -   95 steam connection opening -   96 feed-through conduit -   97 mixing nozzle chamber -   98 (electrical) contacts -   99 mixing nozzle opening -   100 drinks preparation system -   101 coffee machine -   103 placement platform -   105 coffee outlet -   106 front -   107 milk frother platform -   108 outlet hood -   110 connection location -   110′ alternative interface -   111 steam delivery location -   112 hot water and/or steam delivery location -   113 electric contacts -   121 electronics unit -   151 air connection -   152 air feed-through -   155 tube portion -   195 activation -   195′ alternative activation -   200 drinks vessel 

The invention claimed is:
 1. An appliance that can be docked onto a drinks preparation machine and is adapted to prepare frothed milk, comprising a connection for steam produced by the drinks preparation machine, and a milk frothing unit with a gear pump which, at an inlet side, is connected to a milk feed conduit and to an air feed, and comprising an interface for electrical current supplied from the drinks preparation machine, for operating the gear pump, and a mixing nozzle on a path of milk delivered by the gear pump, wherein the milk, the steam as well as the air can be fed to the mixing nozzle.
 2. The appliance according to claim 1, wherein the mixing nozzle is designed such that steam flowing in from the connection achieves a suction effect and air is sucked into the mixing nozzle on account of this suction effect.
 3. The appliance according to claim 2, wherein the air feed into the mixing nozzle comprises a valve which, given inflowing steam, automatically opens on account of a vacuum in the mixing nozzle, said vacuum being produced by way of this inflowing steam and achieving the mentioned suction effect.
 4. The appliance according to claim 3, wherein the valve is a duckbill valve.
 5. The appliance according to claim 1, wherein the mixing nozzle is designed such that steam flowing in from the connection achieves a suction effect which acts upon milk flowing into the mixing nozzle.
 6. The appliance according to claim 1, wherein the mixing nozzle is arranged downstream of the gear pump in the flow direction of the milk.
 7. The appliance according to claim 6, wherein the mixing nozzle is arranged directly above a milk froth outlet, through which outlet the frothed milks exits from the appliance.
 8. The appliance according to claim 1, wherein the air feed to the gear pump is provided with a closing device that is operable to selectively close the air feed.
 9. The appliance according to claim 8, wherein the closing device comprises an activatable valve unit and air can also be fed to the mixing nozzle via the valve unit.
 10. The appliance according to claim 1, comprising a milk frothing unit with the gear pump, wherein the milk frothing unit comprises a housing, by way of which a gear pump chamber is formed, said chamber being delimited to the bottom by a seal, wherein the seal is designed as a continuous object with at least one valve opening for sucked milk.
 11. The appliance according to claim 1, comprising a further connection for water and/or steam, which is/are delivered by the drinks preparation machine, wherein a conduit to a location upstream of the gear pump in the flow direction leads from this further connection.
 12. The appliance according to claim 1, comprising a container for receiving milk, as well as a milk frothing unit with the gear pump, wherein the milk frothing unit and the container with regard to their geometry are matched to one another such that the milk frothing unit can be placed on the container in a manner closing off the milk container.
 13. The appliance according to claim 12, comprising a lid which fits onto the milk frothing unit placed on the container, as well as directly onto the container.
 14. A drinks preparation system comprising an appliance according to claim 1, as well as a drinks preparation machine, onto which the appliance can be coupled. 